Production of artificial filaments



7 Oct 5, 1943- w. l. TAYLOR ETAL PRODUCTION OF ARTIFICIAL FILAMENTS Filed June 3, 1 941 WI- TAYLOR w POOL NVENTOKS mM VEYS Patented Oct. 5, 1943 PRODUCTION OF ARTIFICIAL FILAMENTS William Ivan Taylor and William Pool, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware Application June a, 1941, Serial No. 396,390 In Great Britain July 2, 1940 12 Claims.

This invention relates to the production of artificial filaments and is particularly concerned with the spinning of artificial filaments by the dry or evaporative method.

In the spinning of artificial filaments by the dry or evaporative method the spinning solution, e. g. a solution ofcellulose acetate or other organic derivative of cellulose in acetone, is extruded through a spinning jet containing a number of orifices, so that the solution emerging from the orifices in the form of a number of filaments, enters anevaporative atmosphere in which the filaments harden and set by theevaporation of the volatile solventtherein. Al-

though in many cases the number of orifices in a single jet-is limited by the size of thread that it is desired to produce, there are various applications of dry-spun continuous filaments in which jets can advantageously be used having a number-of holes far in excess of the number rerectly used'as such. 'For example, if the continuous filaments are intended to be cut into staple fibre, considerable economy would result if the number of holes per jet enabled extrusion to conform with the maximum. drying capacity of the cell containing the jet. Again, a thread intended to be stretched to produce filaments of great strength (or, when cut, strong staple fibre) may have a very large number of filaments. There are, however, certain difliculties arising in starting the operation, and in bringing about initially the clean flow of the. spinningsolution through each of the orifices of a spinning jet Y containing a large number of orifices.

every orifice is spinning the operation cannot Until be regarded as started, and the time spent in this operation depends. on the number of orifices in the jet. Consequently the number of orifices is limited by the time that can economically be allowed for starting the spinning with the jet as a whole.

It is an object of the present invention to 20 quired for the production of threads to be d1- supply. In this way it may be ensured that each of the orifices in the jet is flowing freely and that there is freedom from air bubbles liable to clog the jet in the space immediately behind' the jet. Although a solvent for the base material of the spinning solution, e. g. the same solvent as the one actually used in the solution, may be used, the liquid with which the jet is filled is advantageously the spinning solution itself, which, in orderto restrict to a minimum evaporation of solvent in the interval of i applying the filled jet to the source of supply, should be cold. The attention needed from the time the jet is applied to the pressure supply to the time when stable spinning is reached is much reduced, possibly because the exclusion of air from the inside of the jet proper prevents gel f0 ori ces. A plasticizer may likewise be used.

For the purpose of carrying out the invention the spinning jet together with filter sheets and associated parts forming with the jet a unit to 'be attached to the source of supply of spinning solution may first be attached to a header. supplying for example, cold spinning solution under pressure, at a temperature of about 25 C. The liquid is supplied at a speed substantially lower than the speed at which spinning,solution is supplied during spinning, and is allowed to run for about 10 to 15 minutes, the liquid emerging during the latter part oi this time from the spin-'- ning orifices and clearing the jet of any air bubbles that may have been trapped therein. The jet assembly is then removed and attached as quickly as possible to the source of supply of spinning solution from which spinning is to take place. the spinning is started in the usual way. If cold spinning solution is the liquid supplied, the jet may point upwards from the header to facilitate the complete forcing out of the air. When the jet is removed from the header, the viscous nature of the solution prevents the solution from running out of the jet, and the jet filled with solution may be inverted and applied to the usual pendant supply pipe of the dry-spinning facilitate the clearing of any jet orificesethat may be blocked. Thus the jet may be subjectedation likely to produce blocking of the- After attachment the jet is wiped andleasing tight orifices, promotes free flow through the orifices.

The carrying out of the invention will not be described in greater detail with reference to the accompanying drawing, in which Fig. 1 is a-diagram-Jnatic section of the upper end of a dry-spinning cell with the jet in position;

Fig. 2 is asection' of a jet fitting assembled onthe supply pipe;

Fig. 3 is an elevation corresponding to Fig. 3

but showing the jet fitting dis-assembled;

Fig. 4 shows apparatus for filling ajet with cold spinning solution; and

Fig. 5 is a part-section of the pneumatic tool shown in use in Fig. 1.

Referring to Fig. 1, l is a spinning cell through which air is drawn upwardly by suction applied to an outlet pipe 2. fed by a pump (not shown) to a candle filter 3 depending from-the top of the cell, a jet fitting 4 being screwed to the'bottom of the filter. A door 5 in'the side of the cell provides access to the filter and jet.

The construction of the jet fitting "4 is shown in'Fig. 2. The jet proper comprises a flanged metal disc 6 having a circular or other arrangement of orifices I. The jet is clamped to a member 8, a layer 9 of filter material and a perforated-plate in spaced from the layer 9 being interposed between the jet flange and the member 8. The member 8 is screwed to a short pipe --H the upper end'of which is provided with a conical seat l2 towards which a ball 13 is urged by a spring I4. .A nut I5 provides for the attachmentof the pipe II to a member l6 screwed on the supply pipe] l1- leading from the bottom moved from the pipe 23, the ball valve l3 serving to prevent escape of spinning solution as the fitting is transferred to the spinning cell and screwed in place on the member IS. The jet fitting and the solution contained in it being cold, little evaporation of solvent takes place during .the transfer of the jet fitting to the member l6. As soon as the jet fitting is in place, spinning solution, which is heated by its passage through the filter 3, is forced into the jet fitting and causes the cold spinning solution to be expressed, the cold spinning solution ensuring that by the time the hot solution reaches the orifices the passage through the orifices is maintained clear.

The perforated plate l0 has orifices less in 4 size but greater in number than the orifices 1 in The spinning solution is the jet 6 and thus serves to hold back or break up formations of small gels in the spinning solution which might lodge in the jet orifices proper and bring about stoppage of flow. The fiow capacity of the disc Ill is greater than that of the jet cell and it therefore becomes immaterial if some of the small holes in the disc l0 become completely stopped.

When the initial mass of spinning solution that has collected on the lower face of the jet 6 has been wiped away, it may be found that one or of the filter 3, The member "5 is provided with a conical seat 18 towards which a ball l9'is urged by gravity and by the pressureof the spinning solution passing through the pipe I! and through an eccentric passage 20 in a block 2| which serves to retain the ball I9 within the member l6.

The jet fitting .4 is removed from the member.

16 by. slackening the nut l5. When the jet fitagainst the seat l8 to prevent the entry of air into the member l6. Upon reassembly of the jet fittingon the member IS a washer 2|, interposed between the member IG'and the pipe ll, presses the balls l3, l9 away from their respective seats and an eccentric hole 22 in the washer permits the flow of spinning solution to the jet.

When a new, jet is to be fitted to the candle 3, a jet fitting 4 with jet 6, filter 9, and perforated plate Ill duly assembled, is screwed on to an upwardly directed branch pipe 23 to which cold spinning solution under pressure is supplied by a pump 24 from a header 25. Spinning solution is forced through the jet for about I lution to'be forced through all the orifices I of the jet. With the jet fitting thus entirely filled with cold spinning solution the fitting is remore of theorifices I are still extruding with difliculty. To deal with this, use is made of the small hand pneumatic'tool 28 conveniently connected by flexible hose 21 to an air line 28. The head of the tool is fitted with a wooden peg 29 which is applied to the face of the jet to subject the latter to' rapid vibration, especially in thephates are suitable plasticisers for filling the jet before spinning.

- Having described ourinvention, what we desire to secure by Letters Patent is:

1.-In the starting of a spinning operation for artificial filaments by the dry or evaporative method, filling the spinning jet with a liquid compatible with the spinning solution, and then :applying the jet filled with the liquid to the source of supply of spinning solution.

2. In the starting of a spinning operation for artificial filaments by the dry or evaporative method, filling the spinning jet with a solvent for the base-material of the spinning solution, and then applying the jet filled with the liquid to the source of supply of spinning solution.

3. In the starting of a spinning operation for artificial filaments by the dry or evaporative method, filling the spinning jet with spinning solution at a temperature below that of the solution to be spun, and then applying the jet filled with the solution to the source of supply of spinning solution.

4. In the starting of a spinning operation for artificial filaments of an organic derivative of cellulose by the dry or evaporative method, filling the spinning jet with a liquid compatible with the solution of said organic derivative of cellulose to be spun, and then applying the jet filled with the liquid to the source of supply of spinning solution.

5. In the starting of a spinning operation fer artificial filaments of cellulose acetate by the dry or evaporative method, filling the spinning jet with a solvent for cellulose acetate, and then applying the jet filled with the solvent to the source of supply of spinning solution.

6. In the starting of a spinning operation for artificial filaments of cellulose acetate by the dry or evaporative method, filling the spinning jet with a solution of cellulose acetate at a temperature below that of the solution to be spun and then applying the jet filled with solution to the source of supply of spinning solution.

'7. In the starting of a spinning operation for artificial filaments by the dry or evaporativemethod, filling the spinning jet with a liquid compatible with the spinning solution, then applying the jet filled with the liquid to the source of supply of spinning solution and then applying vibrating pressure to the surface of the spinning 9.'In the starting of a spinning operation for artificial filaments by the dry or evaporative method, filling the spinning jet with a solvent for the base material of the spinning solution, then applying the jet filled with the solvent to the source of supply ofspinning solution and then applying vibrating pressure by'means of a pneumatic hammering tool to the surface of the spinning jet in order to promote free flow through the jet orifices.

10. In the starting of a spinning operationfor artificial filaments by the dry or evaporative method, filling the spinning jet with spinning solution at a temperature below that of the solution to be spun, 'then applying the jet filled with the solution to the source of supply of spinning solution and then applying vibrating pressure by means of a pneumatic hammering tool to the.

surface of the spinning jet in order to promote free fiow through the jet orifices.

11. A spinning jet connection for facilitating the attachment of a spinning jet filled with liquid to a source of supply of spinning-solution, said connection comprising a valve on the end of the source of supply of spinning solution, an attachment to carry the spinning jet, and a valve on said attachment, said valves being adapted to close when the spinning jet is removed from the source of supply and to open when the spinning jet is attached to the source of supply.

12. Spinning jet connection for facilitating the attachment of a spinning jet filled with liquid to a source of supply of spinningsolution, said connection comprising a ball valve on the end ofthe source of supply of spinningsolution, an attachment adapted to carry a spinning jet, a springloaded ball valve on'said attachment and a. discadapted to be secured between said attachment- 

